Lucas Giolito and the Long-Awaited Comeback

Are we finally seeing the Lucas Giolito performance that we waited so long for? Once pegged as a “top-of-the-rotation demigod,” Giolito has struggled to find any consistency in the majors. Through the month of May, he’s got the highest K% of his career at 29.2% and the largest K% increase in MLB from 2018 to 2019 with a 13.1% jump. He’s got an average fastball velocity of 93.4 mph, up exactly one tick from last season, and has also added 148 rpm to his heater. Giolito has been more aggressive in terms of overall zone percentage, with the third-largest MLB increase from 2018 to 2019 at 6.8%. Even while down in a hitter’s count, he’s found ways to battle back in the zone, something he was below league average in last season:

Batters are having a tougher time squaring him up and he’s even added some vertical break on his fastball and curveball:


He’s added almost two inches of ride to his fastball, from 8.87 to 10.46, making it above average in ride. A significant change in his vertical release point may have something to do with all this, as Giolito has gone almost over the top with his delivery, as shown in this Brooks Baseball chart:

The difference is also evident during game action as well. Here’s his 2018 release point:

And here is his 2019 release point:

For a pitch that generates that much ride, he’s not exactly locating it in the top third of the zone as consistently as we’d like:

However, if we split this up to look at Giolito against lefties, this is where we could find the difference in his improved fastball:

He loves jamming that fastball inside to left-handed hitters, and it’s been effective to start the season, resulting in 22.78% whiffs-per-swing, which would be a career high. However, his fastball is getting crushed against righties to the tune of a .388 wOBA and a 94.4-mph exit velocity, at a 54.56% usage rate. Perhaps a decrease in fastball pitch usage to righties could be helpful for Giolito? The success of his changeup and slider could make that alteration possible:

He throws his slider almost exclusively to righties, and although it generates below-average lateral movement, it has still managed to remain an effective pitch in his career. Using the following Baseball Savant strike zone, his pitch percentage in zones 6, 9, and 14 is at an all-time high.

In 2018, his percentage of sliders to righties in the zones mentioned was 42.8%. Fast forward to the 2019 season, and he’s throwing in those zones at a 65.2% clip, good for 6th in baseball for RHPs to RHBs. His slider whiff-per-swing percentage has skyrocketed from 35.32% to 58.06%, with the league average at 33.71%.

Although he added an inch of fade to his changeup from 2018 to 2019, he still rates just about average in terms of movement for the pitch. However, Giolito also has an 11.7-mph gap between his CH and FB, giving him another legitimate plus pitch in his arsenal right now. He’s also found a consistent horizontal release point to finally work with, moving from -2.4 feet to -1.44 feet, as evidenced in the following PITCHf/x graphics:

Giolito throws his changeup in the zone 64.1% of the time, which is good for No. 1 in baseball, a 20% increase from his 2018 total of 44.4%. While pitchers slowly begin to throw more changeups out of the zone (the league average is 61% in 2019), Giolito has stayed away and it’s still paid off big time. He’s managed to register 36.67% whiffs-per-swing on the pitch in 2019, 9.41% greater than league average so far, while also posting an above-average ground-ball rate on the pitch at 50% and the fourth-best called-strike percentage at 20.5%.

Although he’s gone from -8.31 to -9.91 inches of drop on his curveball, Giolito just can’t seem to find his groove with his former money pitch, even with the above-average drop. Although it’s still a small sample size, it’s been crushed at 92.5 mph to begin the season, good for fifth-worst in baseball (minimum 10 results) and his location with the pitch hasn’t exactly helped:

He had his most success with the pitch in his 2018 season, where he managed to use that drop more to his advantage and finished with 20% whiffs-per-swing and an 86.9 mph exit velocity:

If Giolito could ever find the feel and location for that former plus curveball again, that would give him another weapon in his arsenal to work with. He’s already got the strong mix of secondaries, with the out-of-zone slider and in-zone changeup, along with an improving fastball. After a few mediocre seasons on the South Side, Giolito looks to finally be back on the path to becoming relevant again and could play a big role in the Sox rotation for years to come.

  • All data from Baseball Savant or FanGraphs

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